1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device by processing a substrate while removing films formed on parts of a semiconductor manufacturing apparatus.
2. Description of the Prior Art
In a process of forming a silicon (Si)-based film by using a hot wall type chemical vapor deposition (CVD) apparatus, source gas and etch gas are supplied to the inside of a reaction furnace through a gas supply pipe. However, when gas is supplied from a gas supply source, films are deposited on quartz components (e.g., a reaction tube, a boat, and the gas supply pipe (including a nozzle)) as well as wafers, and if the thickness of the films exceeds 3 μm, the films may be stripped off and form particles.
Therefore, it is necessary to clean the quartz components periodically, and moreover, it is necessary to replace the quartz components with new components according to the wear of the quartz components. Wet etching can be performed (to remove Si-based films by using an etchant such as fluoroacetic acid and hydrogen fluoride) each time wafers are processed. However, in this case, since washing and drying processes are also necessary, maintenance time increases, and thus maintenance efficiency decreases. In addition, when a quartz component is detached, the inside of the reaction furnace is exposed to the outside atmosphere and thus can be contaminated. Therefore, it is not preferable to maintain a highly clean state.
For these reasons, dry etching may be alternatively performed to remove Si-based films by introducing cleaning gas (e.g., ClF3) into the reaction furnace in a state where the quartz components are disposed in the apparatus in a nitrogen (N2) atmosphere.
However, when an Si-based film forming process is performed, since the inside pressure of the gas supply pipe (including a nozzle) used for supplying source gas is higher than the inside pressure of the reaction furnace, a thicker film is deposited on the inside of the source gas supply pipe as compared with the inside of the reaction furnace. Therefore, stresses are accumulated in the gas supply pipe due to the thicker film. If cleaning gas is supplied through the gas supply pipe in which stresses are accumulated, the film deposited on the inside of the gas supply pipe is rapidly etched, and thus the accumulated stresses are rapidly released. This causes breakage of the gas supply pipe such as cracking of the gas supply pipe. Moreover, due to resultant particles and replacement of the gas supply pipe after a dry cleaning process, maintenance efficiency decreases.